Radar Observer · Performance — PRF vs Maximum Range
The pulse repetition frequency (PRF) is kept low on long range scales because:
- AA high PRF increases maximum range
- BThe set must wait for echoes from distant targets to return before transmitting again, avoiding second-trace (multiple-trace) returns✓ Correct
- CLow PRF improves bearing accuracy
- DPRF has no relation to range
Explanation
Between pulses the radar listens for returns; the maximum unambiguous range is set by the listening interval (1/PRF). On long ranges the PRF is lowered so echoes from far targets return before the next pulse — too high a PRF on a long scale produces second-trace echoes from beyond the nominal range.
Authority: IMO Performance Standards for Radar; Bowditch
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